GM preparing cleaner Duramax diesel engine

GM has allowed short drives in the next-gen, meaner, cleaner Duramax diesel engine, although in the lighter-duty G-van (Chevy Express/GMC Savana) application. Changes to the new D-max are significant, including revisions to the cylinder block to improve rigidity and reduce noise, an upgrade to 2000-bar (29,000-psi) piezo injectors, and a complete system-hardening to tolerate 20-percent biodiesel mixtures.

Along with the upgrades to the lines, seals, and fittings required for the B20 fuel comes a switch away from post-injection of diesel fuel in the cylinder, in favor of injecting diesel fuel directly into the exhaust in order to purge the soot that collects in the diesel-particulate filter. This eliminates cylinder-wall wetting that can lead to oil dilution, which is exacerbated by biodiesel’s higher boiling point.

This approach also works better with the selective catalytic reduction (SCR, urea-injection) NOx catalyst system that will come standard with the Duramax.

Feeding this system is a 5.8-gallon urea tank that is expected to last for an entire oil-change interval, but if the truck is used for extremely heavy towing it may be expended earlier. As fitted to the vans and their chassis-cab applications, the LGH engine produces 250 horsepower and 500 pound-feet of torque. Exact specs for the 3/4-ton pickup application have yet to be disclosed but expect that they'll be at least as high as the current ratings (365 hp/660 lb-ft).

The unladen test van accelerated briskly and seemed quite responsive to rolling onto the throttle. The system incorporates a noise-reducing block so the fact that you're driving a diesel vehicle won't be that obvious. [via motortrend]